Share this story

Richard Alley's studies of the role of ice sheets in climate change have earned him various awards, a PBS special, and have made him a repeat performer at the meetings of the American Association for the Advancement of Science. When I first saw him speak a few years ago, he argued that the ice sheets of Antarctica and Greenland play a huge role in controlling sea levels. Mountain glaciers don't hold nearly as much water, while the thermal expansion of water in the oceans is a slower and more predictable process.

The ice sheets, in contrast, have been a big unknown. At the time, we didn't yet fully understand how much of them might melt, or how quickly they might dump water into the oceans.

Alley was back at this year's meeting, and his news was mixed. As he predicted in his earlier appearance, a few years of intensive study have helped narrow down some of the uncertainties. And, while the news is (relatively) good in Greenland, some of the results from Antarctica are decidedly worrying.

Going with the flow

Alley described an ice sheet as a big pile of ice that wants to spread slowly, a spreading that would put more of its mass into the oceans and raise sea levels. Anything that speeds up that spreading is bad news for us, since it would give us less time to get carbon emissions under control and create a more sudden rise in sea levels that would be harder to adapt to.

Two of the big unknowns that Alley's been studying can help accelerate the spread of the ice cap into the oceans. In Greenland, the summer melt creates large lakes of meltwater on the ice cap's surface, which drain suddenly, pouring huge volumes of water to the base of the ice. This can lubricate its flow over the underlying rocks, and accelerate the ice cap's spread. In Antarctica, this sort of melting isn't as much of an issue; instead, exit glaciers carry ice from the continent's interior to the ocean. Because these flow slowly through narrow outlets, he compared them to flying buttresses, the architectural features that hold up the pile of rocks that comprise Medieval cathedrals.

In the time since his last talk, Alley felt that we'd come to terms with Greenland. The water from the summer melt does reach the bottom of the ice sheet, and it does accelerate its movement to some degree. But the terrain underneath the ice is very bumpy, which limits how easily the ice can flow even when water is present. As such, he thinks that Greenland's contribution to future sea level rises will be relatively slow and steady—it will melt, but it won't do anything sudden and unexpected.

The news was worse from Antarctica. Here, work by Alley and others has focused on the dynamics of exit glaciers that hold back the flow of large glaciers near the West Antarctic Peninsula. The key thing that regulates the flow of these glaciers is what's called a "grounding line," or the place where the glacier's end is in contact both with the ocean floor and with the ocean itself (this is in contrast to the floating ice that sometimes spreads past this site).

While a glacier is on the grounding line, Alley said there are a lot of feedbacks that tend to keep it there. The sediment it carries gets dumped there, raising the ocean bottom. The Earth itself, with less ice above it, rebounds from the weight that was present during the last ice age, also keeping the contact between the ice and ocean floor intact. These and a few other feedbacks help keep the grounding line stable even as rising temperatures would otherwise tend to force the glacier to break up and retreat.

The problem is that, when the feedbacks are finally overcome, the grounding line fails catastrophically, and the ice tends to retreat rapidly to the next potential grounding line. This behavior shows up in models of the glacier's behavior, and it's apparent in imaging of the ground under the ice, where there's little sign of retreat from past melts outside a handful of grounding lines.

What does this mean for the particular glacier Alley chose to focus on? If its current grounding line fails, there's another a bit behind it that it will likely retreat to. If that one fails, however, there's enough ice between it and the one behind that to raise sea levels by two meters. And, from a geological perspective, that retreat could occur in a flash—fast enough to obviate any long term plans for adaptation.

Science has a head-on collision with policy

That's worrying on its own. But it's a special problem, Alley argued, because of the way policy makers have approached sea level rise. To begin with, they've tended to assume that any rise will be gradual and slow. Alley blamed this in part on the reports from the Intergovernmental Panel on Climate Change—its most recent report provided a conservative estimate, and failed to convey the large uncertainties in what we know about ice sheet behavior.

The other problem, in his view, is that economists also assumed that people would be rational actors, and either take preventative measures or stop investing any money in property that would inevitably wind up under water. Neither of those have happened. Alley said that he and many others had been teaching introductory geology classes that discuss how conditions in New Orleans made something like Katrina inevitable, but that didn't actually result in any investment in infrastructure to handle the problems. Similarly, some of the problems New York City faced during Sandy had been accurately predicted a number of years in advance.

The lack of economic rationality, however, is also apparent after the events have occurred. Rather than focus on a rational evaluation of future risks, we've generally pumped money into rebuilding in precisely the same places that have just been wiped out.

A better model for how to deal with this risk, in Alley's view, is how we handle road safety. For most of us, the typical commute involves, at worst, being stuck in a bit of traffic and having the radio play some awful music. The worst case is a long, bumper-to-bumper crawl during an hour-long test of the emergency broadcast system. Only very rarely does any of us get smacked into by a drunk driver. And yet we put a tremendous effort into dealing with that rare possibility, including funding awareness campaigns, dedicating police enforcement activity, and designing safety features into our vehicles.

Given what he's seen in the Antarctic, Alley thinks we should be following something more like the drunk driver model.

What does this mean for the particular glacier Alley chose to focus on? If its current grounding line fails, there's another a bit behind it that it will likely retreat to. If that one fails, however, there's enough ice between it and the one behind that to raise sea levels by two meters.

Global sea levels by two meters just from this one glacier? Holy crap.

The drunk driver model works for drunk driver issues, because the deleterious effects of driving drunk are immediate and obvious.

The same is not true of man-made climate change.

The effects of them are. Like Sandy, or Katrina.

Climate change doesn't cause hurricanes, but it does makes them more severe.

I don't think the drunk drive model will work either because we humans are a reactionary species -- the results of drunk driving are very visible and immediate, and can't be argued against with bad science. Until the same percentage of people who believe that drunk driving is wrong, come to accept that AGW is real, there's no way the government will be able to enact a similar model of preparedness.

What does this mean for the particular glacier Alley chose to focus on? If its current grounding line fails, there's another a bit behind it that it will likely retreat to. If that one fails, however, there's enough ice between it and the one behind that to raise sea levels by two meters.

Global sea levels by two meters just from this one glacier? Holy crap.

Kind of scary how complex systems can surprise, huh? The most frightening possibility for me has been the unknowns surrounding the behavior of large reserves of stored greenhouse gasses in tundras and methane clathrates. If some of the theories are right, tipping points in the temperature and composition of the ocean could cause runaway escalations in greenhouse gases on much faster scales than we've typically anticipated. I don't know if this is likely in today's environment, but the largest extinction event in Earth's history, the Permian-Triassic, might have been caused by clathrate release. Pretty heady stuff.

It is interesting that I just heard a report about how some people are crying out for dikes in New Jersey to protect them from the next hurricane. They don't seem to care that this can create the effect of a giant bowl full of water if the water gets higher than the dikes or enough rain falls.

I would be interested to see what the Netherlands is doing. A good section of the country is below sea level. It would also be interesting to see a map of how much land worldwide would be lost at 2 metes.

The drunk driver model works for drunk driver issues, because the deleterious effects of driving drunk are immediate and obvious.

The same is not true of man-made climate change.

The effects of them are. Like Sandy, or Katrina.

Not to most people. Climate science is complex. Most people can't wrap their head around it. Couple that with the fact that the climate has been causing us problems since the beginning of time and it is hard for people to link the current climate risks to something we are doing.

On the other hand, getting drunk and doing something stupid is something we've all done. The effects of crashing a car are immediate and obvious. Forming a link is very simple. And yet, people still drive drunk.

It is interesting that I just heard a report about how some people are crying out for dikes in New Jersey to protect them from the next hurricane. They don't seem to care that this can create the effect of a giant bowl full of water if the water gets higher than the dikes or enough rain falls.

I would be interested to see what the Netherlands is doing. A good section of the country is below sea level. It would also be interesting to see a map of how much land worldwide would be lost at 2 metes.

Well, we dont drown in a fish bowl of our making if that's what you are thinking

Just building dikes is nice but its only part of the solution, obviously, you also have to have ways to get rid of water which we do by pretty much constant pumping. A rise of 2 meters would still leave us safe behind our sea defenses but it would mean that a conflagration of high tide and storm could breach the dikes then, not that this is news to us, we're already spending billions over the next few years to fortify existing sea defenses and changing others. There are also spillways and land that's intended as flood gronds btw.

Our willingness to rebuild New Orleans - which is doomed to sink into the Gulf of Mexico - more or less as-is, and the dismal failure of places on the northern Atlantic coast to prepare for the occasional hurricane is just depressing. People will build right up to the high tide line then scream loudly when the ocean rudely marches past it and demand that someone compensate them for their stupidity.

In general, people only react to obvious, in your face problems. Abstract, "we are driving over a cliff" warnings that cannot be "seen" are discounted.

Fundamentally, Climate Change warnings mean that people have to drastically change their lifestyle, and possibly even more severe than just lifestyle. There is no way people will change without an obvious, life threatening condition.

I find it an amazing aspect of humanity that we all tend to ignore the problem that is looming on the horizon, but will spend enormous amounts of time and energy ignoring that same problem. I am talking about all of the people who denied that smoking causes cancer. (And the young people who smoke.) The ones who fought and fight seatbelts. Those who refuse to stop eating things that are making them extremely unhealthy. (myself included) It is astounding the lengths that we will go to lie to ourselves and everyone around us.

Our willingness to rebuild New Orleans - which is doomed to sink into the Gulf of Mexico - more or less as-is, and the dismal failure of places on the northern Atlantic coast to prepare for the occasional hurricane is just depressing. People will build right up to the high tide line then scream loudly when the ocean rudely marches past it and demand that someone compensate them for their stupidity.

Yeah. In retrospect the feds offering highly subsidized flood insurance, which shortly preceded the initial boom in high risk coastal building was a major mistake. Unfortunately there's not an easy way to extricate ourselves from it now. Just slashing the subsidies would trigger an enormous political mess, and the repeat loss prevention provisions that have been used in parts of the interior (requiring isolated midwest farmhouses to be rebuilt on top of earthen mounds piled above the 100y flood line, and buying out home owners in narrow flash flood prone valleys) are impractical from engineering or cost standpoints in heavily developed coastal regions.

I find it an amazing aspect of humanity that we all tend to ignore the problem that is looming on the horizon, but will spend enormous amounts of time and energy ignoring that same problem. I am talking about all of the people who denied that smoking causes cancer. (And the young people who smoke.) The ones who fought and fight seatbelts. Those who refuse to stop eating things that are making them extremely unhealthy. (myself included) It is astounding the lengths that we will go to lie to ourselves and everyone around us.

What does this mean for the particular glacier Alley chose to focus on? If its current grounding line fails, there's another a bit behind it that it will likely retreat to. If that one fails, however, there's enough ice between it and the one behind that to raise sea levels by two meters.

Global sea levels by two meters just from this one glacier? Holy crap.

Kind of scary how complex systems can surprise, huh? The most frightening possibility for me has been the unknowns surrounding the behavior of large reserves of stored greenhouse gasses in tundras and methane clathrates. If some of the theories are right, tipping points in the temperature and composition of the ocean could cause runaway escalations in greenhouse gases on much faster scales than we've typically anticipated. I don't know if this is likely in today's environment, but the largest extinction event in Earth's history, the Permian-Triassic, might have been caused by clathrate release. Pretty heady stuff.

Agreed -- the permafrost carbon sink is also something that worries me as well -- once that starts melting...damn.

Our willingness to rebuild New Orleans - which is doomed to sink into the Gulf of Mexico - more or less as-is, and the dismal failure of places on the northern Atlantic coast to prepare for the occasional hurricane is just depressing. People will build right up to the high tide line then scream loudly when the ocean rudely marches past it and demand that someone compensate them for their stupidity.

Yeah. In retrospect the feds offering highly subsidized flood insurance, which shortly preceded the initial boom in high risk coastal building was a major mistake. Unfortunately there's not an easy way to extricate ourselves from it now. Just slashing the subsidies would trigger an enormous political mess, and the repeat loss prevention provisions that have been used in parts of the interior (requiring isolated midwest farmhouses to be rebuilt on top of earthen mounds piled above the 100y flood line, and buying out home owners in narrow flash flood prone valleys) are impractical from engineering or cost standpoints in heavily developed coastal regions.

Whatever. There's nothing retrospect about it - this all could have been assertained well before the disasters happened. Null_interface's point still stands without your poltical double speak.

I think the drunk driving model would be an excellent example of what NOT to do. Despite more and more laws, and more and more violations of the Constitution, drunk driving accidents and deaths have not decreased.

Where did you get this idea from?

"Since NHTSA began recording alcohol-related statistics in 1982, drunk driving fatalities have decreased 52% from 21,113 in 1982. Since the inception of The Century Council and our national efforts to fight drunk driving, drunk driving fatalities have declined 35% from 15,827 in 1991. (Source: NHTSA/FARS, 2011)"

Our willingness to rebuild New Orleans - which is doomed to sink into the Gulf of Mexico - more or less as-is, and the dismal failure of places on the northern Atlantic coast to prepare for the occasional hurricane is just depressing. People will build right up to the high tide line then scream loudly when the ocean rudely marches past it and demand that someone compensate them for their stupidity.

Yeah. In retrospect the feds offering highly subsidized flood insurance, which shortly preceded the initial boom in high risk coastal building was a major mistake. Unfortunately there's not an easy way to extricate ourselves from it now. Just slashing the subsidies would trigger an enormous political mess, and the repeat loss prevention provisions that have been used in parts of the interior (requiring isolated midwest farmhouses to be rebuilt on top of earthen mounds piled above the 100y flood line, and buying out home owners in narrow flash flood prone valleys) are impractical from engineering or cost standpoints in heavily developed coastal regions.

Whatever. There's nothing retrospect about it - this all could have been assertained well before the disasters happened. Null_interface's point still stands without your poltical double speak.

Richard Alley's studies of the role of ice sheets in climate change have earned him various awards, a PBS special, and have made him a repeat performer at the meetings of the American Association for the Advancement of Science. When I first saw him speak a few years ago, he argued that the ice sheets of Antarctica and Greenland play a huge role in controlling sea levels. Mountain glaciers don't hold nearly as much water, while the thermal expansion of water in the oceans is a slower and more predictable process.

2 Things:

first - he needs to close his shirt.

second - basic physics and studies of N. America since the previous Ice Age (go look them up) have concluded that as the Ice melts away from those given land masses - the lack of added mass and weight on top of them will raise them up. So unless his insight takes that into account - his conclusions will not be a global outcome.

But like any community choosing to live in areas prone to natural change - Yes - folks living on the beach might be underwater if/ when it happens. Folks living under water currently -- New Orleans - Netherlands - etc - better build higher dikes.

Poor Polar Bears.

The previous Ice Age had ice sheets on North America, as you said, which means North America rebounded upward when the ice was removed. We are not currently in an Ice Age and there are no ice sheets on North America to my knowledge. If you remove ice from Antarctica and put it in the oceans, the only rebounding land mass will be Antarctica, not North America, nor Europe, nor Africa, nor Asia, nor the many sea-level archipelagos. Therefore his conclusions are correct for all land masses that don't currently have massive ice sheets on them, which are pretty much every land mass humans inhabit.

Two meters of global sea rise will have a devastating impact on the global economy, if not any human cost. And the saddest part is that no one (as a collective group) will see it coming. Even if the change is lightning speed from a geological standpoint, it will still take years. This gradual change will only encourage us to build higher and thicker barriers between us and the oceans instead of undertaking mass relocations from effected areas. When these barriers fail during various times in various places (Katrina, New York/New Jersey) the results will become ever more catastrophic. There will come a point when the sustainability of these regions bankrupt our nations.

Our willingness to rebuild New Orleans - which is doomed to sink into the Gulf of Mexico - more or less as-is, and the dismal failure of places on the northern Atlantic coast to prepare for the occasional hurricane is just depressing. People will build right up to the high tide line then scream loudly when the ocean rudely marches past it and demand that someone compensate them for their stupidity.

Yeah. In retrospect the feds offering highly subsidized flood insurance, which shortly preceded the initial boom in high risk coastal building was a major mistake. Unfortunately there's not an easy way to extricate ourselves from it now. Just slashing the subsidies would trigger an enormous political mess, and the repeat loss prevention provisions that have been used in parts of the interior (requiring isolated midwest farmhouses to be rebuilt on top of earthen mounds piled above the 100y flood line, and buying out home owners in narrow flash flood prone valleys) are impractical from engineering or cost standpoints in heavily developed coastal regions.

Whatever. There's nothing retrospect about it - this all could have been assertained well before the disasters happened.

I would be interested to see what the Netherlands is doing. A good section of the country is below sea level. It would also be interesting to see a map of how much land worldwide would be lost at 2 metes.

I kind of doubt that anyone in the Netherlands has any interest in making decisions based on pure fantasy, given the billions of euro they invest here in dykes. IPCC reports talk of 30cm sea level rise by 2100.

"And, from a geological perspective, that retreat could occur in a flash—fast enough to obviate any long term plans for adaptation."

It seems alarmist, and perhaps rightfully so, but are we talking ten years or ten thousand years? Both are blinks of an eye from a geological perspective.

Tens of thousands of years are probably enough for some species to adapt to changing environments and survive. Ten or a hundred years is probably not. If this happens in that ten to one hundred year time frame then many species of plants and animals could go extinct practically over-night.

Of course, extinction is the ultimate end point for every species and there's nothing particularly special about the species that exist in this time in comparison to the species that existed in previous times. But still, rapid extinctions of many species could have a serious ripple effect across the entire planet. This has the potential to be a shake up as fundamental as the great extinction events of the past.

second - basic physics and studies of N. America since the previous Ice Age (go look them up) have concluded that as the Ice melts away from those given land masses - the lack of added mass and weight on top of them will raise them up. So unless his insight takes that into account - his conclusions will not be a global outcome.

Yes, post-glacial rebound is an observable and ongoing phenomenon, but it only affects areas previously covered in glacial sheets, namely the Canadian Shield, and on a magnitude of about a centimeter a year, so unless you're suggesting we all move up there and learn to live with black flies, muskeg and polar bears, I'm not sure how this helps the population of the Eastern Seaboard, where there's no rebound happening.

So, IPCC is talking 30 cm sea rise. This guy insists on 2 meters, and some other dude 10 m. Now please give the stage to those who think it would be 0 cm.

Anesthetize your AGW gag reflex for a moment, would you? Ignoring whether humans have an impact on, well, anything, he's pointing out that if this one glacier gives way we'll have an extra 2 meters of water to deal with everywhere on earth.

Are you going to say, "no, that could never happen for any reason, never ever, nope!" and leave it at that? Would you possibly consider that we ought to be taking this possibility into account when, say, siting nuclear reactors, chemical factories and cities?

I wouldn't say we should never build anything close to the water line, but the more we could limit that activity to structures we can afford to lose, the better. But that's just me, I'm not busy playing the victim because nobody will listen to me cry about how the world will always be how it is today.

In the past, I was a skeptic. The problem for me has been that there was little clear evidence to explain the difference between natural temperature cycles and man made influences on these cycles. We know weather patterns historically AREN'T stable. Comments like the one above (only sane people know there's a problem) is complete fiction, because most people don't bother with fact - they go by what the papers tell them. In reality, the story is very complex.

CO2 levels have varied all over the place (including being much higher than they are today). CO2 concentrations is another matter. Temperature fluctuations v/s temperature maximums ... for TAFKAP to say that it's bleedingly obvious is a myth for most of the population, unless they spend some serious time researching.

However, I am happy to quote the following (which I found from the link above),"In the scientific literature, there is a strong consensus that global surface temperatures have increased in recent decades and that the trend is caused mainly by human-induced emissions of greenhouse gases."